Ex: (P1) and (P2) start off on a screen and hoards come from different directions. Whoever kills the most monsters in a certain time frame will gain points. The monsters will get harder as you progress. There could be settings involved with this. You would try to balance this through ratings on players and how strong they are by what they clear and how fast during their freeplay. Just an Idea. Run with it, change it, just a thought I wanted to put out in public.
Given you could go anywhere with this. It's just an IDEA. If you have more opinions please share! I just want Blizzard to have some ideas thrown at them. You never know what could happen.
Personally, this would be really fun. Going against someone and killing monsters as fast as possible and that determines how many points you get. I mean sheesh, you could even activate legendaries dropping too, but if you chose to pick them up you lose your ability to beat the other person in monster kills. "legies could disappear on a timer after they drop". IDK just blabbing. I love hearing everyone's opinions so shoot away. I know this isn't clear... but I would like to see what others make of this blueprint.